Recognition of multiple sclerosis (MS) attacks relies mostly on clinical assessment. However, their definition based on McDonald criteria refers mostly to timing and when dealing with clinical features is rather ambiguous: "...of the kind seen in multiple sclerosis." This is heightened in clinically isolated syndromes of the brainstem/cerebellum (CISB), where clinical manifestations can be manifold. This study aimed to describe the clinical features of patients with CISB to improve clinical recognition of patients with brainstem manifestations at the onset of their MS. To this end, we conducted a retrospective analysis of case notes of consecutively recruited patients with CISB assessed within 3 months of symptoms onset. Seventy-five patients were included. Most common brainstem-specific symptoms were: diplopia (68%), facial sensory symptoms (32%) and gait disturbance (31%). Adjusting for follow-up times, total number of symptoms and presence of other brainstem-specific symptoms, only the presence of facial sensory symptoms was predictive of (a lower risk of) conversion to clinically definite (CD) MS (Odds ratio: 0.086; p = 0.007). Neither the total number of brainstem-specific, non brainstem-specific nor the sum of both predicted conversion to CDMS. Results indicate that diplopia, facial sensory symptoms and gait disturbance occur in more than 30% of patients with CISB. Facial sensory symptoms are less associated with conversion to CDMS.